According to CNN Money’s report, the average lifespan of a bridge in the U.S. is 50 years. More than 66,000 bridges in the nation are classified as deficient; among those, the average age is 65 years old. The average age of American bridges is 43 years old, so within the next decade, another 25 percent of the nation’s bridges will reach age 65, when they will become more likely to be classified as deficient.

Map data show that Pennsylvania has the largest amount–24.5 percent–of structurally deficient bridges, while Nevada and Florida each have the least amount–2.2 percent–of structurally deficient bridges.

Oklahoma, New York and Louisiana have each seen an increase of more than 50 deficient bridges since 2011, giving these three states the greatest amount of bridge deterioration in the U.S.

Despite these figures, the total number of deficient bridges has been reduced in recent years. Pennsylvania, for example, has been working to improve its bridges; the state repaired 8 percent of its deficient bridges since 2011.